Basic Usage Steps

• Write NavigatorPanel implementation
• Register implementation class in xml layer

Writing NavigatorPanel implementation

Implementing NavigatorPanel interface is easy, you can copy from template basic implementation BasicNavPanelImpl.java.

• Instantiation: Your implementation of NavigatorPanel is instantied automatically by the system if you register it in a layer (described in next step). See detailed Instantiation rules to understand which kind of instantiation possibilities are on the plate.

• getComponent method: Simply create and return your UI representation of your data in Swing's JComponent envelope. Just be sure that you don't create new JComponent subclass per every call, as performance will suffer then.

• panelActivated and panelDeactivated methods wraps an 'active' life of your panel implementation. In panelActivated, grab your data from given Lookup, usually by looking up its asociated DataObject or FileObject to take data from. Also remember to attach listeners to lookup result, perhaps also to data itself and trigger UI update with new data. Code will typically look like this:
  

          /** JavaDataObject used as example, replace with your own data source */
          private static final Lookup.Template MY_DATA = new Lookup.Template(JavaDataObject.class);
  
          public void panelActivated (Lookup context) {
              // lookup context and listen to result to get notified about context changes
              curResult = context.lookup(MY_DATA);
              curResult.addLookupListener(/** your LookupListener impl here*/);
              Collection data = curResult.allInstances();
              // ... compute view from data and trigger repaint
          }
              

  Do *not* perform any long computation in panelActivated directly, see below.
  In panelDeactivated, be sure to remove all listeners to context given to you in panelActivated.

• Long computation of content: What if rendering your Navigator view takes long time, more than several milliseconds? Right approach is to create and run new task using RequestProcessor techniques, each time when panelActivated call arrived or your listeners on data context got called.
  While computing, UI of Navigator view should show some please wait message.

Registering NavigatorPanel impl in a layer

Declarative registration of your NavigatorPanel impl connects this implementation with specific content type, which is type of the document, expressed in mime-type syntax, for example 'text/x-java' for java sources. Infrastructure will automatically load and show your NavigatorPanel impl in UI, when currently activated Node is backed by primary FileObject whose FileObject.getMimeType() equals to content type specified in your layer.

Writing layer registration itself is easy, you can again copy from template layer Basic Navigator Registration Layer.

• System looks up for navigator providers only in Navigator/Panels folder, nowhere else.

• Content type is specified as cascade of subdirectories under Navigator/Panels directory. Mime-type syntax is recommended and handy for specifying content type.
  It is not compulsory though, so if you need to make up a name for your content type, just go for it. (more below)

Advanced Content Registration - Linking to Node's Lookup

There may be situations where linking between your Navigator view and activated Node's primary FileObject is not enough or not possible at all. This simply happens when the data you want to represent in Navigator are not accessible through primary FileObject or DataObject. Usual example is Multiview environment, where more views of one document exists.

The solution is to bind content of your Navigator view directly to your TopComponent. Then, whenever your TopComponent gets activated in the system, Navigator UI will show th content you connected to it.

• Choose your content type, could be either well known or arbitrary, say 'text/my-amazing-type' and do all basic steps described in above use case.

• Implement NavigatorLookupHint interface like this:

          class AmazingTypeLookupHint implements NavigatorLookupHint {
              public String getContentType () {
                  return "text/my-amazing-type";
              }
          }
               

• Alter your TopComponent to contain your NavigatorLookupHint implementation (AmazingTypeLookupHint in this case) in its lookup, returned from TopComponent.getLookup() method.

• Another option you have is to alter lookup of your Node subclass instead of directly altering lookup of your TopComponent. See Node.getLookup() method. Then Navigator will show your desired content whenever your Node subclass will be active in the system.
  However, keep in mind that this option is less preferred, because it only uses implementation detail knowledge that default implementation of TopComponent.getLookup() includes also results from lookup of asociated Node. So this approach will stop working if you change default behaviour of TopComponent.getLookup() method.

Programmatic activation of NavigatorPanel

Programmatic activation of specific navigator panel activates and shows navigator panel in navigation area, as if user had selected the panel manually. API clients are expected to use programmatic activation to activate/select preferred panel from a set of available panels.

• Get the instance of NavigatorPanel implementation that you want to activate/show in navigator area.
  See Instantiation rules.

• Call NavigatorHandler.activatePanel(NavigatorPanel panel)
  .

Setting activated node of Navigator window

Sometimes clients need to alter activated Nodes of Navigator window, to better represent Navigator area content within the whole application. See TopComponent.getActivatedNodes() and TopComponent.Registry.html#getActivatedNodes() to find out what activated nodes of TopComponent and whole system mean.

• In your implementation of NavigatorPanel, implement method getLookup() to return Lookup instance filled with Node(s) that you want to set as activated Nodes of Navigator window.

• Be sure to update Lookup content properly, for example using InstanceContent as follows:

          class MyNavigatorPanel implements NavigatorPanel {
          
              /** Dynamic Lookup content */
              private final InstanceContent ic;
              /** Lookup instance */
              private final Lookup lookup;
              
              public MyNavigatorPanel () {
                  this.ic = new InstanceContent();
                  this.lookup = new AbstractLookup(ic);
              }
          
              public Lookup getLookup () {
                  return lookup;
              }
  
              /** Call this method when activated Nodes change is needed, 
              * for example when selection changes in your NavigatorPanel's Component
              */
              private void selectionChanged (Node oldSel, Node newSel) {
                  ic.remove(oldSel);
                  ic.add(newSel);
              }
              
              ... impl of rest of your NavigatorPanel
              
          }
               

Adding UndoRedo support to the navigation view

Some complex navigation views need support for undoing and redoing edit changes done either directly in the view or in document which the view is representing.

• Implement your navigation view as NavigatorPanelWithUndo, which is NavigatorPanel interface with extra method getUndoRedo().

• All other things remain the same as with basic NavigatorPanel usage. UndoRedo support returned from NavigatorPanelWithUndo.getUndoRedo() is propagated to the Navigator TopComponent and returned as its UndoRedo support. For details see TopComponent.getUndoRedo() and UndoRedo interface.

• Example of NavigatorPanelWithUndo implementation:

          class MyNavigatorPanelWithUndo implements NavigatorPanelWithUndo {
          
              /** UndoRedo support, substitute with your impl */
              private final UndoRedo undo = new UndoRedo.Manager();
          
              public UndoRedo getUndoRedo () {
                  return undo;
              }
              
              ... rest of the NavigatorPanelWithUndo impl ...
  
          }
               

Removing active Node/DataObject related NavigatorPanels from Navigator window

In certain situations it's not desired to show NavigatorPanel implementations related to DataObject of active Node in Navigator window. Typically you need to have active Node of some type, so that actions in the system works properly. But you don't want to show NavigatorPanels that "come" with such active Node.

• Implement interface NavigatorLookupPanelsPolicy, return kind of policy that suits you from getPanelsPolicy() method.

• Put implementation instance into your TopComponent's subclass lookup, see TopComponent.getLookup() for details.

• Now when your TopComponent becomes active in the system, found panels policy is used to limit/affect set of available NavigatorPanel implementations.